Circuit arrangement for energizing load apparatus



Jan. 23, 1962 A. R. CORNELL 3,018,410

CIRCUIT ARRANGEMENT FOR ENERGIZING LOAD APPARATUS Filed April 5, 1960 3 Flg. 2

Fig. 3 q- 5 WITNESSES INVENTOR H Argcie R. Corn ell ATTORNEY United States Patentofifice 3,018,410 Patented Jan. 23, 1962 3,018,410 CIRCUIT ARRANGEMENT FOR ENERGIZING LOAD APPARATUS Archie R. Cornell, Avon Lake, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 5, 1960, Ser. No. 20,110 7 Claims. (Cl. 315-438) The present invention relates to electric circuit arrangements for energizing load apparatus, and, more particularly, to circuit arrangements which can be used to initiate a discharge in and to provide continuing operation for electric discharge devices, such as fluorescent lamps.

Since an ionized path, for enabling the flow of a current through a discharge device, can normally be provided only with the application of an elevated voltage, relative to the voltage which is necessary to maintain the discharge once initiated, it is necessary that the circuit arrangement which is used to energize a discharge device, or discharge devices, be enabled to supply an elevated voltage for starting purposes. In addition, it is necessary that the circuit arrangement be enabled to supply a lower voltage to sustain the resulting discharge current With a ballasting effect and thereby to preclude high power expenditures and adverse effects upon the life of the discharge device which would otherwise result through continued application of the elevated starting voltage. Of course, the circuit arrangement can also provide other functions which might particularly be called for to enable the specific discharge device with which it is being used to meet fully its operational purpose. For example, in certain types of fluorescent lamps the discharge electrodes are necessarily preheated before a discharge can occur and, when so required, the circuit arrangement can be arranged so as to provide additionally the preheating function.

With regard again to the starting function of the circuit arrangement, it is desirable that the discharge be initiated almost concurrently with the energization of the circuit arrangement and that it be accomplished substantially without an oscillatory response. Otherwise, or if oscillations do occur in the flow of current during the start-up period, objectionable oscillations in light output, if the discharge device is in the form of a fluorescent or other type of lamp, can occur. In the lighting art, the objectionable state of oscillation just noted is conventionally referred to as flickering.

Considered fundamentally, the discharge current may be defined as a mathematical function of certain parameters in the circuit arrangement, including the negative resistance characteristic of the discharge device itself, and, of course, certain environmental factors, such as temperature and humidity. Because, in qualitative terms, the noted circuit parameters and environmental factors have a more marked effect upon the oscillatory state of the discharge current under transient conditions, the oscillations of the discharge current are, ordinarily, evidenced during the start-up period.

By providing the discharge current so that its existence as a function of circuit parameters and environmental factors is not characterized with oscillations, either through the removal of circuit parameters found to enhance the oscillatory effect during transient conditions or through uniquely arranging the circuit components so that the bearing of the circuit parameters and the environmental factors upon the production of discharge oscillacharacterized with benefits not conventionally obtainable.

Considered from a mathematical frame of reference, any oscillatory component of the function which conventionally describes the discharge current would then substantially be omitted to remove the objectionable flickering effect.

In applications in which the circuit arrangement is to be used to energize a plurality of discharge devices, such as generally indicated in US. Patent 2,558,293 of A. E. Feinberg, entitled Apparatus for Starting and Operating Gaseous Discharge Devices, issued June 26, 1951, it is desirable that the respective currents through the devices be maintained substantially equal for, if this result is not obtained, unnecessary energy transmittal losses can accrue, in the case of the devices being serially operated, to the operating character of the circuit arrangement and, in any event, the respective rates of expanding the useful life of the lamps and the wattage or light output of the lamps can be unbalanced.

Although a given level of power operation might not lead to objectionable effects in the current equalization matter for a given circuit arrangement, a different level of power operation, for example an elevated one, might result in an objectionable difference between the lamp currents for the given circuit arrangement. Just as in the oscillatory matter considered previously, current equalization can be obtained by removing or reducing the influence of any circuit parameters or other factors which ordinarily enhance the differential current or undesired effect. Of course, the attainment of a minimized differential current and the substantial removal of oscillatory effects are only to be achieved without impairing other necessary circuit functions, such as ballasting or optimizing power factor.

It is in the perspective of the remarks thus far made that the present invention will be better understood.

Accordingly, it is an object of the invention to provide a novel circuit arrangement for supplying energy to discharge devices which enables substantial preclusion of oscillatory effects.

It is a further object of the invention to provide a novel circuit arrangement for supplying energy to discharge de vices which enables a plurality of discharge devices to be supplied with substantially equal currents.

It is another object of the invention to provide a circuit arrangement including novel means for ballasting discharge devices energized by the arrangement.

These and other objects of the invention will become more apparent upon consideration of the following detailed description of an illustrative embodiment of the invention as related to the attached drawing, in which:

FIGURE 1 is a schematic view of a circuit arrangement which is formed in accordance with the principles of the invention;

FIG. 2 is a top view illustrating the physical form which can be accorded to the inductive and magnetic components of the circuit arrangement shown schematically in FIG. 1; and,

FIGS. 3, 4 and 5 are vector diagrams which represent the interrelations among certain of the voltages associated with the circuit arrangement of FIG. 1 prior to the initiation of discharge, during initiation of the discharge, and during normal operation of the arrangement,

respectively.

With regard to the broad precepts of the invention, inductive means are provided for supplying elevated voltages to a plurality of discharge devices to enable the devices to be started sequentially and to supply the discharge devices in serial order with a normal operating voltage when started. To prevent the discharge device current from exceeding rated values, ballasting means are also provided, with a portion of the inductive means also forming a portion of the ballasting means. The interrelation of the inductive means and the ballasting means with the discharge devices is such that in addition to the functions already noted being provided, oscillatory effects, upon the discharge currents through the devices, are eliminated and the respective discharge currents are substantially equated with each other. To illustrate more clearly but not to limit these broad principles of the invention, the detailed description will now be set forth. In order to energize a plurality of discharge devices, illustrated here as a pair of fluorescent lamps 11 and 12, of the instant start or slimline type, a circuit arrangement is formed to transmit electrical energy from a source 13 of fluctuating or alternating potential. The circuit arrangement 10 includes inductive means 14 for amplifying or transforming the voltage of the source 13 and capacitive means 16 for enabling a ballasting effect to be imposed upon the current through the lamps 11 and 12. I

To enhance the electromagnetic induction in the inductive means 14, a core 18 is employed, as schematically illustrated in FIG. 1 and as structurally illustrated in FIG. 2. Magnetization of the core 18 is accomplished through the use of a primary Winding 20, and secondary windings 22 and 23 are wound upon the core 18 in aiding relation with the primary winding 20 and a secondary winding 24- is wound upon the core 18 in bucking relation with the primary winding 20 in order to provide operative voltages for purposes to be indicated hereinafter. The primary winding 20 and the secondary winding 22 are connected in serial relation to be disposed, through respective conductors 26 and 28, in parallel relation with the lamp 11. Similarly, the secondary windings 22, 23 and 24 are connected in a serial branch of the circuit arrangement 10 to be disposed, through conductors 30 and 32, in parallel relation with the lamp 12. In the latter serial circuit branch, the capacitance means 16 are also serially included, here in connected relation between the secondary Winding 24 and the lamp 12. In addition, means for suppressing or shorting radio or other relatively high frequency currents, to minimize interference with communication devices, are included in the arrangement 10 in the form of a capacitor 34 which bridges or bypasses the primary winding 20.

With reference to FIG. 2, the inductive means 14 can be provided with the physical form indicated, including a three-legged construction of the core 18, with laminations, if desired, and a spaced positioning of the windings 20, 2223, and 24. The latter or spaced relation results in determinable portions of the flux created by the current flowing in any one of the windings being linked, respectively, with other ones of the windings. As such, the secondary windings 22, 23 and 24 are provided with a correspondingly determinable amount of leakage reactance, relative to the winding 20 with the leakage reactance of the windings 22 and 23 relative to the winding 20 being considerably greater than th leakage reactance of the winding 24 through the employment of a magnetic shunt path or leg 36 including an air gap 38. The operational purpose of the described character of the windings 22, 23 and 24 will subsequently become evident. To control the magnitude of the magnetizing current in the primary winding 20, and to provide added control for the coupling between the primary winding 20 and the secondary windings 22 and 23, a bridged gap 40 can be included in central leg 19 of the core 18.

The size and type of conductors and the number of turns which are provided to fulfill the intended functions of the windings 20, 22, 23 and 24 can be determined through design considerations. For similar reasons, the amount of magnetic material in the core 18 as well as the character of the aforementioned core laminations, if any, and the size of the gaps 38 and 40 can be determined by any skilled artisan. Although the core 18 as shown in FIG. 2 is provided with three legs through the use of two E subassemblies and an I subassembly, assemblies having different magnetic path arrangements or subassemblies having different configurations, though nevertheless forming a three-legged core, can be used, if

desired, so long as the basic principles of the invention are applied in using any alternately selected arrangement of the core.

With reference again to FIG. 1, the operation of the circuit arrangement 16; will now be described. Clearly, once the voltage of the source 13 is applied to the primary winding 20, with which it forms a complete serial circuit loop, a magnetizing current commences to flow in the primary winding 20 to create magnetic flux in the core 18 including the central core leg 19, The portion of the flux which is coupled with the secondary windings 22, 23 and 24 effects respective induced voltages in these windings.

Since the winding 22 is connected to aid the primary winding 20, the vectorial sum of the voltages across the windings 2t) and 22 is sufiicient to initiate a discharge current through the lamp 11. This is clearly indicated in the vector diagram of FIG. 3, in which it is shown that the primary voltage V and the voltage V D, across the winding 22, aid to provide a starting voltage V across the lamp 11. Similarly, the vectorial sum of the voltages across the windings 22, 23 and 24 is applied across the lamp 12, but since the winding 24 is connected in bucking relation with the winding 22, the resulting voltage is not initially sufficient to enable the lamp 12 to be started. This is also clearly indicated in FIG. 3, in that the voltage V across the lamp 12 is shown to be the resultant of the vectorially summed secondary voltages V and V The initiated discharge through the lamp 11 news sanly flows through the secondary winding 22 to create additional flux in the adjacent portion of the core leg 19 and resultingly in the shunt leg 36 of the core 18. Since the discharge current through the lamp 11 is necessarily out of phase with the inductively lagging magnetizing current of the primary winding 20, it is clear that the flux created in the core leg 19 or shunt leg 36 by the noted discharge current is out of phase with the flux created by the magnetizing current. It follows that, as the shunt leg 36 contributorily provides for the winding 22 a relatively high leakage reactance relative to the primary winding 20, the net flux which links the winding 22 is somewhat out of phase with the net flux which links the winding 20 thereby providing for the winding 22 an induced voltage which is correspondingly out of phase with the voltage across the winding 20.

Additionally, the secondary winding 23 is also provided with an induced voltage which is substantially in phase with the induced voltage across the winding 22 since the winding 23 is wound upon the core 18 to be linked by substantially the same net flux which links the secondary winding 22. Finally, the net resulting flux in that part of the core 18 which links the secondary winding 24, being in bucking relation with the primary winding 20, induces a voltage in the winding 24 which is out of phase with the windings 20, 22 and 23 but which, when vectorially added to the induced voltage across the windings 22, and 23, is suflicient in magnitude to provide for initiating a discharge through the lamp 12.

The diagrammatic representation in FIG. 4 clearly indicates the phase relation between the winding voltages subsequent to a starting of the lamp 11 but prior to a rtarting of the lamp 12. It is represented that the voltage V which is the voltage across the windings 22 and 23, when added vectorially with the voltage V provides a voltage V which is sufficient in magnitude to start the lamp 12.

With the establishment of conduction through the lamp 12, the current through the lamp 11 becomes substantially common with the current through the lamp 12 to form, in effect, a serial circuit branch including'the lamps 11 and 12 through which operational energy is supplied by the voltage source 13. As diagrammatically represented in FIG. 5, the discharge voltage V across the lamp 12 and the discharge voltage V across the lamp 11 are sufficient to sustain a discharge through the respective lamps 12 and 11, and when added vectorially to the voltage V across the capacitor 16 and the voltage V across the secondary windings 24 and 23 provide a resultant voltage equal to the source voltage V Clearly, the serial operation of the lamps 11 and 12 can be continued until the energy being supplied by the voltage source 13 is interrupted.

In addition, the amount by which the current through the serial lamp circuit might ordinarily be out of phase with the source voltage can be offset, for example through appropriate adjustment of the magnetizing current by properly sizing the bridged core gap 40 as described previously. Thus, an in-phase relation can substantially be provided between the source current and the source voltage.

To limit the serial operational current through the lamps 11 and 12, the capacitive means 16 along with the reactance of the windings 23 and 24 provide a ballasting impedance. As noted previously, sufficient reactance in the windings 23 and 24 is provided for the ballasting purpose through the employment of flux leakage in the core 18.

In addition, the relatively high leakage reactance of the winding 22 is sufficient to impede substantially any shunting of serial current to the voltage source 13. To enhance substantially this effect, the winding 23 is included in the serial lamp circuit. Clearly, by directing the flow of lamp current through the winding 23, a flux -is created in the core leg 19 of which the major portion is directed through the shunt leg 36 only to couple the windings 22 and 23. With a coupling of the winding 23 in this manner, the latter flux provides an inductive effect for the aforementioned ballasting function. Through a linking of the winding 22, the same flux provides an inductive effect which enables the winding 22 substantially to block the entry or shunting of any current from the serial lamp circuit.

In this manner, as noted earlier to be desired in circuit arrangements which supply a plurality of discharge devices, the current through the lamp 12 is substantially equated with the current through the lamp 11. As disclosed conventionally, the lamp 11 could be connected through the conductor 28 to the circuit junction E rather than the circuit junction D, but the enhanced impeding function of the Winding 22 would then not be available. The latter notation is particularly significant in instances 'in which the lamps 11 and 12 or other discharge devices are to be supplied with an elevated value of voltage, such as 277 volts, as compared, for example, with 118 volts. It has been found experimentally that by connecting the windings 22 and 23 as shown in FIG. 1, the differential value between the current through the lamps 11 and 12 can be restricted not to exceed 15 milliamperes when the exemplified value of 277 volts is employed. On the other hand, the differential current cannot be so minimized with the use of the 277 volt sunplv if the conductor 28 is attached to the junction E rather than the junction D. notwithstanding that such a connection might prove satisfactory if the exemplified value of 118 volts were used.

At the outset of this description it was also noted that oscillatory effects in circuit arrangements for supplying energy to discharge devices are desirably to be minimized or removed. In this connection, with the inclusion of the capacitance means 16 serially with the lamp which is started second in time, in this instance the lamp 12. rather than the lamp which is started first in time, in this instance the lamp 11, any tendency of the circuit arrangement to be unstable with resulting oscillations during the start-up period has been found experimental y to be virtually non-existent. Moreover, an additional benefit is achieved with the use of the present invention in that the discharge through the exemplified lamps 11 and 12 has been found experimentally to approach significantly a sinusoidal function. Of course, the more closely a load current behaves in accordance with a sine function rather than in accordance with a discontinuous or other type of function characterized with peaking, the more economic the delivery of load current becomes because the current can then be provided with a lesser root mean square value for any given amount of delivered load energy.

Although the oscillatory problems might not be encountered in the instances in which slimline lamps are operated from the exemplified 118 volt supply when the capacitance means 16 is connected, for example, between the junction D and the lamp 11 rather than between the junction F and the lamp 12, such a connection can and often does result in oscillatory problems when the exemplified 277 volt supply is used. However, as noted above, by connecting the capacitance means 16 at the position disclosed here, oscillatory or flickering problems are obviated even with the use of the exemplified or other sources of higher voltages.

As noted in general terms previously, the current through the lamps 11 and 12 can be determined to be a function of circuit parameters and environmental factors, such as temperature and humidity. In view of the nonlinear nature of the circuit arrangement, a rigorous analysis to determine this function is not at all feasible, except perhaps for academic purposes. Suffice it to note that in the instance in which the conductor 28 would be connected to the junction E rather than, as here, to the junction D and in which the capacitance means 16 would be connected between the lamp 11 and the junction E rather than, as here, between the junctions F and G, the circuit parameters and environmental factors are such that resonant or oscillatory effects, occasioned, for example, by the relation of the circuit capacitative reactance to the circuit inductive reactance in a subnormal temperature environment, are not precluded, particularly, as already noted, with the use of higher valued voltage sources. On the other hand, by providing a circuit arrangement as disclosed here, the pertinency of environmental factors and circuit parameters with respect to instability is substantially removed. In the interest of completing the mathematical frame of reference, it is to be noted that, in the 'circuit arrangement disclosed here, the differential current between the lamps 11 and 12 is minimized or eliminated altogether in that the circuit parameters are interrelated substantially to prohibit any portion of the load or operational current from being shunted to the source 13. Of course, a fuller qualitative analysis of the differential current problem has already been presented.

It is to be noted, of course, that the explanation of {the circuit operation set forth here, particularly in the matter of the vectorial representation of circuit voltages, is subject to the fact that the voltages are not necessarily sinusoidal in form. The reason for this lies, at least in part, in the fact that the lamps 11 and 12 ordinarily behave non-linearly. However, for the purpose of explanation the presented analysis remains valid in qualitative terms.

In the foregoing description, the mode of operation of an arrangement of specific circuit elements has been related to point out the principles of the invention. The

. operational mode has been explained on the basis of general theoretical concepts and if a more rigorous or accurate explanation is to be obtained. the applicability of these basic principles is not to be affected thereby, for the presented explanation has been set forth only in an attempt to clarify and not to limit the invention. The description, therefore, has only been illustrative of the invention,.and, accordin ly, it is desired that the invention be not limited by the arrangement or embodiment described here. but, rather, that it be accorded an interpretation consistent with the scope and spirit of its broad principles.

What is claimed is:

1. A circuit arrangement for energizing a plurality of discharge devices, said arrangement comprising inductive means being energized by a voltage source and including a primary winding and at least a pair of secondary windings, said primary winding and one of said secondary windings being connected in aiding voltage relation across at least one of said discharge devices, the other of said secondary windings being connected in bucking voltage relation with said one secondary winding to energize the remainder of said discharge devices, said primary and said one secondary windings providing sufficient voltage to initiate a discharge in said one discharge device, said one and said other secondary windings providing su'lficient voltage to initiate a discharge in said remainder of said discharge devices subsequent to the commencement of the discharge in said one discharge device, said one and said remainder of said discharge devices being substantially serially related with said voltage source when energized, and means for ballasting the current through said one and said remainder of said discharge devices including capacitance means, said capacitance means being connected serially with said one and said other secondary windings and said remainder of said discharge devices to preclude the occurrence of oscillatory effects which would otherwise occur if physical variables pertinent to the oscillatory effects were to attain otherwise critical values.

2. A circuit arrangement for energizing at least a pair of discharge devices, said arrangement comprising inductive means having a plurality of secondary portions and a primary portion being energized by a voltage source, means for connecting said portions to start said devices in seriatim and subsequently to operate said devices substantially in series relation, and means for ballasting said discharge devices including capacitance means, said capacitance means being connected serially in a starting circuit loop which includes the discharge device last started but not the discharge device first started and portions of the inductive means which are employed in starting the discharge device last started so as to preclude the occurrence of oscillatory efiects which would otherwise occur if physical variables pertinent to the oscillatory efi'ects were to attain otherwise critical values.

3. A circuit arrangement for energizing a plurality of discharge devices, said arrangement comprising inductive means being energized by a voltage source and including core means and a primary winding and first, second and third secondary windings, said primary winding and said first secondary winding being connected in aiding voltage relation across at least one of said discharge devices, said second secondary winding being connected in aiding voltage relation with said primary and first secondary windings and said third secondary winding being connected in bucking voltage relation with said primary and first secondary windings, said secondary windings being connected across the remainder of said discharge devices, said primary and said first secondary windings providing sufficient voltage to initiate a discharge in said one discharge device, said secondary windings together providing sufficient voltage to initiate a discharge in said remainder of said discharge devices subsequent to the commencement of the discharge in said one discharge device, said one and said remainder of said discharge devices being substantially serially related with said voltage source when energized, said first and second secondary windings being located commonly on a leg of said core means, and means for ballasting the current through said one and said remainder of said discharge devices, the serial circuit quality of said one discharge device relative to said remainder of said discharge devices being enhanced through the efiect of said aiding second secondary winding.

4. A circuit arrangement for energizing a plurality of discharge devices, said arrangement comprising inductive means being energized by a voltage source and including core means and a primary winding and first, second and third secondary windings, said primary winding and said t5 first secondary windings being connected in aiding voltage relation across one of said discharge devices, said second secondary winding being connected in aiding voltage relation with said primary and first secondary windings and said third secondary winding being connected in bucking voltage relation with said primary and first secondary windings, said secondary windings being connected across the remainder of said discharge devices, said primary and said first secondary windings providing sufficient voltage to initiate a discharge in said one discharge device, said secondary windings providing sufiicient voltage to initiate a discharge in said remainder of said discharge devices subsequent to the commencement of the discharge in said one discharge device, said one and said remainder of said discharge devices being substantially serially related with said voltage source when energized, said first and second seconadary windings being located commonly on a leg of said core means, and means for ballasting the current through said discharge devices including capacitance means, said capacitance means being connected serially with said secondary windings and said remainder of said discharge devices to preclude the occurrence of oscillatory effects which would otherwise occur if physical variables pertinent to the oscillatory effects were to attain otherwise critical values, the serial circuit quality of said one discharge device relative to said remainder of said discharge devices being enhanced through the eiTect ofsaid aiding second secondary winding.

5. A circuit arrangement for energizing at least 'a pair of discharge devices, said arrangement comprising inductive means having a plurality of secondary portions and a primary portion being energized by a voltage source, said inductive means being disposed to form a pair of circuit loops for starting said devices in seriatim and being disposed for subsequently operating said devices substantially in series relation, the serially operative circuit branch which enables the serial operation of the discharge devices including at least a pair of voltage opposing ones of said secondary portions of said inductive means, the flux which is created by the discharge device operational current in one of the pair of voltage opposing secondary portions being substantially fully coupled with at least one other secondary portion of said inductive means to enhance the impeding effect against the shunting of any of the operational current through said other portion from said serially operative circuit branch, and additional means for ballasting said discharge devices.

6. A circuit arrangement for energizing at least a pair of discharge devices, said arrangement comprising inductive means having a plurality of secondary portions and a primary portion being energized by a voltage source, said inductive means being disposed to form a pair of circuit loops for starting said devices in seriatim and being disposed for subsequently operating said devices substantially in series relation, the serially operative circuit branch which enables the serial operation of the discharge devices including at least a pair of voltage opposing ones of said secondary portions of said inductive means, the flux which is created by the discharge device operational current in one of the pair of voltage opposing secondary portions being substantially fully coupled with at least one other secondary portion of said inductive means to enhance the impeding effect against the shunting of any of the operational current through said other portion from said serially operative circuit branch, and additional means for ballasting said discharge devices including ca pacitance means, said capacitance means being connected serially in said serially operative branch and in a starting circuit loop which includes the discharge device last started but not the discharge device first started and which includes portions of the inductive means which are employed in starting the discharge device last started thereby precluding the occurrence of oscillatory effects which would otherwise occur if physical variables pertinent to the oscillatory effects were to attain otherwise critical values. 7

7. A circuit arrangement for energizing a plurality of discharge devices, said arrangement comprising inductive means being energized by a voltage source, said inductive means including Winding means of which at least one portion forms one circuit loop with at least one of said discharge devices and of which at least another portion forms another circuit loop with the remainder of said discharge devices, said winding means being operable first to initiate a discharge in said one discharge device and subsequently to initiate a discharge in said remainder of said discharge devices, said one and said remainder of said discharge devices being substantially serially related with said voltage source when energized, and means for ballasting the current through said one and said remainder of said discharge devices including capacitance means, said capacitance means being included serially in said another circuit loop to preclude the occurrence of oscillatory effects which would otherwise occur if physical variables pertinent to the oscillatory eifects were to attain otherwise critical values.

References Cited in the file of this patent UNITED STATES PATENTS 

